Tailor-made Medicine

At our very core — our genes — we're
99.9 percent the same. Mayo Clinic researchers are delving into how the tiny difference that makes us unique can affect, and ultimately improve, the prevention, diagnosis and treatment of diseases.

This new field of study is called individualized medicine. "We want to better tailor treatments to patients," says Eric Wieben, Ph.D., director of the Mayo Clinic Genomics Research Center. Research on individualized medicine is under way at all Mayo Clinic locations on health issues such as Alzheimer's and Parkinson's diseases, diabetes, cardiovascular disease and chemical dependency. Already, researchers have made discoveries that are improving treatments.

The concept of individualized medicine isn't new. It begins whenever a doctor takes a detailed family history. Now, emerging technology allows researchers to better understand how genetic differences affect treatment.

Breast cancer:

Tamoxifen, a drug often used to treat breast cancer, may not be the best treatment option for all women. About 10 percent of Caucasian women have genetic alterations that affect the activity of cytochrome P4502D6, a liver enzyme responsible for tamoxifen metabolism. A study led by researchers at Mayo Clinic and the University of Michigan found that these women were twice as likely to have breast cancer relapse.

Colon cancer:

For people who have a common alteration in gene UGT1A1, the standard dose of a first-line chemotherapy medication used to treat colon cancer causes serious or life-threatening complications. Now, a specialized blood test prior to treatment helps avoid these problems.

Depression:

About 30 percent of patients with major depression disorder don't improve with the first antidepressant prescribed. A deficiency of the gene Cyp4502D6, which is responsible for metabolizing commonly used antidepressant medications, often is the reason. "Knowing there is a deficiency of Cyp450 is especially helpful for high-risk patients with limited ability to articulate how well the medication is working," says Dennis O'Kane, Ph.D., Mayo Clinic scientist.

"Our goal is to make individualized medicine a more widespread and routine part of clinical practice," says Dr. Wieben.